The axes of insect embryos are defined early in the blastoderm stage. Genes involved in this polarization are well known in Drosophila, but less so in other insects, such as the milkweed bug Oncopeltus fasciatus. Using quantitative PCR, we looked at differential expression of several candidate genes for early anterior-posterior patterning and found that none of them are expressed asymmetrically in the early blastoderm. We then used an RNA-Seq approach to identify novel candidate genes that might be involved in early polarization in Oncopeltus. We focused on transcription factors (TFs) as these are likely to be central players in developmental processes. Using both homology and domain based identification approaches, we were unable to find any TF encoding transcripts that are expressed asymmetrically along the anterior-posterior axis at early stages. Using a GO-term analysis of all asymmetrically expressed mRNAs, we found an enrichment of genes relating to mitochondrial function in the posterior at the earliest studied time-point. We also found a gradual enrichment of transcription related activities, giving us a putative time frame for the maternal to zygotic transition. Our dataset provides us with a list of new candidate genes in early development, which can be followed up experimentally.
Bibliographical noteFunding Information:
The authors thank Michal Bronstein technical advice and for building the libraries. They also thank Sharona Elgavish and Yuval Nevo for numerous discussions and preliminary analysis. They are grateful to Barbara Vreede for help and advice throughput this project and for her invaluable expertise in coding. The authors also thank Sivan Ginzburg for his help in coding and other computational matters. Two anonymous reviewers helped focus the manuscript and suggested some important changes. This work was supported by ISF grant #75/11.
© 2017 Wiley Periodicals, Inc.
- early patterning
- transcription factor